Metallic acoustic diaphragm and the manufacture thereof.



METALLIC ACOUST APPLICATION FILED MAY 15, 1911.

E. AUFIERO. lG- DlAPHRAGM AND THE MANUFACTURE THEREOF.

Patented July 13, 1915.

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INVENTOR ,nmianunnnurmno, or BROOKLYN, new YORK.

METALLIGACOTJ STIC DIAPHRAGM AND THE MANUFACTURE THEREOE, i.

To all whom it mayo 072mm. I

Be it known that I, EMANUEL Aurinno, a citizen of the United States, residing at Brooklyn, county of -Kings, and State of New York, have invented new and useful Improvements in Metallic Acoustic Diaphragms and the Manufacture; Thereof, of

which the following is a complete specification.

'My inventon relates to acoustic diaphragms such asare used in telephones,

talking-machines, and particularly in automobilists signaling-devices and the like.

Many defects have heretofore been observed in the behavior of acoustic diaphragms made of metal, such as lack of uniformity of vibration, due to lack of uniformity of sensitivity or lack of uniformity of tension, andthe conseqpent production of secondary vibrating-segments, ripple-vibrations and the like. Attempts have heretofore been made to insure uniformity of vibration, as, for example, by providing the diaphragm with radial or concentric corrugations. These diaphragms, particularly those intended for automobile signals, are generally made of metal of the iron group, particularly, of cold rolled steel, and possess considerable resilience or springiness. When the sheet-steel or the like has been passed through the rollers in the process of manufacture, it is supposed to be of uniform thickness and of the desired density and smoothness; nevertheless, the rolling has produced more or less curvature,.and the steel-sheet is not perfectly flat. And when the diaphragm is cut from the sheet, it retains the slight curvature (being a portion of a cylinder rather than a perfectly flat plane). And when such diaphragm is clamped in place, as'in the automobile horn,- it seems to be held fiat enough, so far as the eye can tell; nevertheless,'there are decided differences of tension around different portions of the clamped periphery, and of course corresponding differences in sensitivity throughout 1ts entire area. rugations above referred to have some efieet,

The cordoubtless, in reducing these differences, of tension, .and to some extent tend toward producing uniformity of sensitivity and homogeneity of vibrativeness.

The present. invention entirely removes the differences. and produces absolute uniformity of behavior .throughout.

The defects referred to are due primarily N V Specification of Letters Patent.

Application filed May 15, 1911. Serial No. 627,170.

Patented July 13, 1915.

(Specimens) to the non-uniformity of tension in the clamped diaphragm; andthat is due to the difference between the tension throughout the convex surface of the unclamped diaphragm and thetension throughout the concave surface thereof (coincident with the slight warping or curvature referred to). I have discovered that uniformity of tension betweenthe two surfaces of the unclam ed diaphragm can be attained, and the iaphragm rendered perfectlyfiat without destroying. its temper and springiness, by increasing the tension of that surface which has less tension (or vice versa); and that this can be effected by producing a plurality 1 of separate and localized and abnormal tension-areas. By abnormal is meant different from the original tension of that portion of the diaphragm. The'selocalized abnormal tension-areas can be produced by striking the diaphragm repeated blows with a hammer, to produce a number of little dents, or by forcing against the diaphragm a suitable die having separated projections adapted to impart to the diaphragm such separated and localized abnormal tensionareas.

In order that my invention may be better I understood, reference -is hereby made to the accompanying drawings to illustrate the same.

In the drawings Figure 1 indicates a diaphragm dented by hammer-blows in carrying out my invention; Fig. 2 indicates, in

exaggerated manner, a cross-section of a portion of a dented diaphragm; and Fig. 3 isa plan indicating a diaphragm upon which my inivention has been carried out by the use of a ie.

The unbroken parallel lines (extending lengthwise of the sheet) in Figs. 1- and 3 are intended to indicate the grain of the metal. The transverse broken lines in Fig. 1 are intended to represent the denting produced by the hammer-strokes. The broken concentric lines 8 and the radial lines 9 in Fig. 3 are intended to represent .the localized areas of abnormal tension produced by the use of a suitable die in a power press. Some of the dents are indicated with great exag geration in Fig. 2, at 7 and 7. The dents of the hammer (or of'the projections of the die) are preferably imparted transversely of the grain (which latter generally runsin the direction of curvature of the sheetmetal). These dents may be so slight as to be searcely visible' on the sili fene treated, and nbt perceptible at all on the opposite side; butthey have the elfecc of permunently flattening the diaphragm (without impairing its springiness); and thereafter'when the diaphragm is clamped in place as in annutomobile-horn, it is under uniform tension and hasuniformi-ty of sensitivity and can vibrate with uniformity.

Having thus described my invention, I claim:

1. A flat and uncorrugated and ungrooved acousfic diaphragm of uniform thickness but with small localized and non-contiguous points of greater density than the rest of the diaphragm.

The process of producing an improved acoustic diaphragm, which consists of imparting smell localized and non-contiguous points of increased density thereto, by imparting hammer blows to the metal at separate and non-contiguous points.

EMANUEL AUFIERO.

' \Yitnesses:

I. T. Rosnxsox, Lotus Runs. 

